arena: tiny clean up.
arena: tiny clean up.

zs634134578/tidb,astaxie/tidb,andelf/tidb,ngaut/tidb,CodeRushing/tidb,andelf/tidb,ngaut/tidb,c4pt0r/tidb,wusphinx/tidb,pingcap/tidb,yangwenmai/tidb,ueizhou/tidb,Cofyc/tidb,spongedu/tidb,kyle-wang/tidb,yuanwhy/tidb,ngaut/tidb,cosmtrek/tidb,c4pt0r/tidb,tiancaiamao/tidb,kyle-wang/tidb,silentred/tidb,cosmtrek/tidb,qiuyesuifeng/tidb,simon-xia/tidb,liyu4/tidb,ngaut/tidb,pingcap/tidb,wusphinx/tidb,qhsong/tidb,liyu4/tidb,kyle-wang/tidb,Nify/tidb,qhsong/tidb,pingcap/tidb,pingcap/tidb,mccxj/tidb,Nify/tidb,mccxj/tidb,c4pt0r/tidb,silentred/tidb,coocood/tidb,c4pt0r/tidb,qiuyesuifeng/tidb,coocood/tidb,pingcap/tidb,spongedu/tidb,yuanwhy/tidb,JinheLin/tidb,zimulala/tidb,astaxie/tidb,XuHuaiyu/tidb,silenceper/tidb,myrice/tidb,JinheLin/tidb,kyle-wang/tidb,c4pt0r/tidb,gaocegege/tidb,c4pt0r/tidb,zimulala/tidb,anywhy/tidb,louishust/tidb,kyle-wang/tidb,8cbx/tidb,EvilMcJerkface/tidb,myrice/tidb,tiancaiamao/tidb,ming-relax/tidb,simon-xia/tidb,8cbx/tidb,silenceper/tidb,zs634134578/tidb,gaocegege/tidb,EvilMcJerkface/tidb,XuHuaiyu/tidb,Cofyc/tidb,pingcap/tidb,ueizhou/tidb,ngaut/tidb,louishust/tidb,CodeRushing/tidb,ngaut/tidb,yangwenmai/tidb,anywhy/tidb,ming-relax/tidb,kyle-wang/tidb